Conventionally, as a safety glass used for a car or the like, an article in which laminated glass is formed by sandwiching solar radiation blocking film between two pieces of sheet-glass, and solar energy incident from the laminated glass is blocked to reduce a load for cooling and feeling of heat has been proposed.
For instance, in Patent Document 1, laminated glass sandwiching a soft resin layer containing thermal radiation blocking metal oxide composed of tin oxide or indium oxide having a fine particle size of 0.1 μm or less between a pair of sheet-glass is disclosed.
In Patent Document 2, laminated glass formed by providing an intermediate layer in which metals such as Sn, Ti, Si, Zn, Zr, Fe, Al, Cr, Co, Ce, In, Ni, Ag, Cu, Pt, Mn, Ta, W, V, Mo; oxides, nitrides, or sulfides of these metals; doped materials of Sb or F, or composites of these materials are disposed between at least two pieces of sheet-glass is disclosed.
In Patent Document 3, window glass for a car in which fine particles of TiO2, ZrO2, SnO2, and In2O3 and a glass component consisting of organic silicon or compounds of organic silicon are intervened between transparent sheet members is disclosed.
Still further, in Patent Document 4, a laminated glass is disclosed, in which an intermediate layer composed of three layers is provided between at least two pieces of transparent glass sheets, and in the second intermediate layer among the three layered intermediate layer, metal such as Sn, Ti, Si, Zn, Zr, Fe, Al, Cr, Co, In, Ni, Ag, Cu, Pt, Mn, Ta, W, V, and Mo; oxides, nitrides, sulfides, or doped materials of antimony (Sb) or fluorine (F), or composites of these materials are dispersed, or an intermediate layer between the first and third layers is made of resin.
However, either of the conventional laminated glasses disclosed in Patent Documents from 1 to 4 has a disadvantage of showing an insufficient solar radiation blocking function when high visible light transmittance is required.
On the other hand, the present applicants proposes, a laminated glass for shielding against solar radiation formed by sandwiching an intermediate layer functioning to block solar radiation between two pieces of sheet-glasses, in which the intermediate layer is composed of an intermediate film containing hexaboride fine particles alone with vinyl resin, or hexaboride fine particles and ITO fine particles and/or ATO fine particles with vinyl resin, or in which the intermediate layer is composed of a solar radiation blocking film containing the above-described fine particles, formed on a surface positioning on the inside of at least one sheet glass, and an intermediate film containing vinyl resin sandwiched between the above-described two pieces of sheet glass, as Patent Document 5. As described in the Patent Document 5, the optical characteristic of the laminated glass for shielding against solar radiation to which hexaboride fine particles alone or hexaboride fine particles and ITO fine particles and/or ATO fine particles are applied has the maximum transmittance in a visible light region and the minimum transmittance in a near-infrared region exhibiting strong absorption. Therefore, compared with the conventional laminated glass described in Patent Documents from 1 to 4, the laminated glass described in Patent Document 5 is improved in visible light transmittance by 70% or more, and in solar radiation transmittance of 50% range.
However, in order to make a practical laminated structure, still higher solar radiation blocking characteristics are required, and the haze value showing the cloudiness of a transparent material is required to be 1% or less for a window material of a vehicle and 3% or less for that of a building. Therefore, even in the laminated glass for shielding against solar radiation described in Patent Document 5, there still remains room for improvement.
[Patent Document 1] Japanese Patent Application Laid-open No. Hei 8-217500 (paragraph 0018)
[Patent Document 2] Japanese Patent Application Laid-open No. Hei 8-259279 (paragraph 0012)
[Patent Document 3] Japanese Patent Application Laid-open No. Hei 4-160041 (claim 1, Publication page 3, upper right column, lines 9-14, and page 3, lower left column, lines 16 to end)
[Patent Document 4] Japanese Patent Application Laid-open No. Hei 10-297945 (paragraph 0018)
[Patent Document 5] Japanese Patent Application Laid-open No. Hei 2001-89202 (paragraph 0012)